The acute and subchronic toxic effects of the pesticide 1,2-dibromo-3-chloro-propane (DBCP) and structurally-related compounds are studied from functional and mechanistic viewpoints. A reported chemo-sterilant in humans, DBCP is no longer manufactured in the U.S., but its presence in ground water and on edible imports and its illegal bulk transport into certain areas of the U.S. require its further toxicological characterization. Effects of DBCP on hepatic, renal and reproductive functions and development are evaluated at several dose levels, after various treatment regimens and under differing conditions such as age, chemical or physical stress and the like. The distribution and disposition of DBCP is being studied in rats, as well as selected aspects of its metabolism and the effects of metabolic modulation on DBCP toxicities. Comparative toxicities of DBCP and its metabolites are being evaluated to ascertain the toxic chemical moiety and to predict whether structurally similar chemicals would produce the same toxic effects as does DBCP.